Dynamic Duo

Grower employs ridge-till and multiple modes of action to hedge against resistant weeds.

Craig Fleishman’s central-Iowa farm is always part of an experiment of some sort searching for a balance between the use of “steel and chemicals” as a way to increase prof ts while maintaining the integrity of the soil.

As a third-grader, he remembers a teacher telling the class about the importance of soil conservation on a day following a dust storm in their area near Minburn.

“That stuck with me,” says Fleishman, who has been involved for years with Practical Farmers of Iowa. The group, founded in 1985, is made up of about 1,500 growers and others interested in agriculture. The nonprofit organization’s mission is to advance prof table and ecologically sound agricultural methods through research conducted by its members.

COVER CROP TEST. Fleishman is two-thirds of the way through a three-year study reincorporating a third crop (oats and red clover) into his rotation. He hopes the additions help to supply nutrition to his corn and soybeans while helping to tamp down weed problems.

As a general rule, he has also tried to control weeds in the absence of some glyphosate-resistant crops because all of his soybeans are non-GMO (genetically modif ed organism).

In his region (like many others), waterhemp has become resistant to glyphosate. So have other amaranthus species. The addition of the oats underseeded with clover is partially an attempt to control these and other weeds. “The oats and clover held back the weeds real well,” Fleishman says. “Otherwise, I did a little spot-spraying with Roundup or 2,4-D.”

NOT SURPRISED. Iowa State University Extension weed scientist Mike Owen has been warning about resistance issues since the early 1980s. He began speaking about “evolved resistance to herbicides, and now, 30 years later, I’m still talking about it.

“Initially, the discussion was that because of the way glyphosate functioned in plants, they would never develop resistance,” Owen says. “When glyphosate was used back then as burndown treatment Or in combination with 2,4-D, it was at lower rates.

“When Roundup Ready technology came to be, glyphosate was now being used alone at the highest rates on essentially different weeds than it had been used on historically,” Owen continues. That has greatly spread the evolution of resistance.

RIDGE-TILL BENEFITS. Fleishman believes his ridgetill system (used for both corn and soybeans) is a great benef t. In ridge-till, seeds are planted in slightly raised mounds, or ridges, built by specific tools on a pass through the field. The ridges were particularly helpful in 2012 and last year, as heavy early-season rains delayed planting. Seeds in ridges could be planted somewhat earlier than other systems and stayed drier as moisture drained away from the ridge.

The troughs between the ridges tend to stay wetter, which, in itself, is a deterrent to growth for many weeds. Once into the season, Fleishman can target needed herbicides onto the growing crops on the ridges while using cultivation tools to destroy any weeds gaining traction between the ridges.

“This isn’t organic, and it isn’t no-till,” Fleishman says, “it is a blend of both. I get about a 50% reduction in herbicide use, and, instead of needing two trips over a field to spray glyphosate, I can usually make one pass to cultivate.”

He employs seven modes of action on his corn and soybeans—five that are chemical and two mechanical. In 2013, all of his corn was Roundup Ready with double or Triple traits, while nearly all the soybeans were non-GMO.

Fleishman’s program in 2013 included:

Fields for corn and soybeans were sprayed with a burndown of Roundup and 2,4-D Ester.

While planting corn, he sprayed Lumax EZ with 32% as a carrier in a 10-inch band.

Soybeans received a preemergence application of Gangster and Warrant in a 10-inch band using the planter.

The ridge cleaners on the planter remove 1 to 2 inches of soil—and the weed seeds in that soil—from the top of the ridges. The cleaned area is moist and improves the activity of the preemergence herbicides.

One or two trips with a ridge-till cultivator removes weeds between the rows. He sometimes has to walk beans to cut broadleaf escapes or uses a tractormounted four-seat bean bar to spot-spray Cobra.

Fleishman also works to keep fencerows clean. In particular, giant ragweed and hemp “tend to creep out into the f eld.” He also uses a tractor-mounted fencerow seeder to establish grass in the fencerows.

Fleishman isn’t oblivious to the reasons why ridge-till isn’t more popular in the central and eastern Corn Belt. “It takes more time to work a ridge-till system, and a guy can move faster over more acres in a conventional or strip-till, or no-till system,” he says. Fleishman farms about 650 acres.

“Also, people don’t like to cultivate,” he adds. “Strip-till has become very popular, and you don’t have to cultivate with strip-till.”

ADD ALTERNATIVES. Fleishman has been using some form of ridge-till since 1981. In his area’s heavy black soils, the raised seedbed seemed to make more sense than no-till, and he uses fewer herbicides. Like most ridge-tillers, Fleishman controls the traff c in his fields— they run equipment in the same paths all the time, year to year.

On more than one occasion, both Fleishman and Iowa State’s Owen have spoken at conferences regarding the need for alternative methods for weed management. They aren’t against the use of Roundup Ready technology, just the lack of use of other tactics for weed control.

“If I were king for a day,” Owen says, “I would have adopted the technologies, but I would also make sure there were suff cient alternatives included to minimize the resistance issue.” He says that one recent survey of 550 weed populations collected from around the country found 60% of them tested as having resistance to more than one herbicide.

Says Fleishman: “I don’t think we’ve seen the worst of resistance issues yet. I don’t know if it has sunk into a lot of farmers yet, but they are starting to get the message.”